New Delhi, August 20, 2020: In a series of serosurveys which are to be conducted by the Delhi Government every month, the results of the second survey are finally out in public. Delhi’s Health Minister Satyendar Jain on Thursday said that 29.1% of people tested in the survey were found to have antibodies present in them, against the coronavirus. The results suggest that a population of about 60 lacs in Delhi has already recovered after being infected by the virus. The samples for the survey were collected across all the districts of Delhi, from August 1 to August 7.
Satyendar Jain said that the improvement across districts can be mapped in the range of 6% to 50%. While the numbers increased only slightly in the North-East District which already had a fairly high percentage in the previous survey of July, South-East Delhi has shown an improvement of about 50%. Additionally, while 28.3% males had antibodies present in them, the percentage of females with antibodies is 32.2%.
The second serological survey was conducted in Delhi where the samples were taken from August 1 to August 7, based on which the report has been released. In the first sero-survey, antibodies were found in 22% of people in Delhi, which means that these people have recovered from Corona. In the second survey, antibodies have been found in 29.1% of the population, which means they have recovered after getting infected. This means that out of the 2 crore people of Delhi, roughly 59 lakh people have recovered and antibodies have been found in them.
Satyendar Jain said, "Different prevalences have been observed in different districts. For instance, antibodies have been found in 29% of people in North East Delhi, 27% in South Delhi, 33% in South East Delhi, 24% in New Delhi, and the difference between the first and the second sero-survey ranges anywhere between 6%-50%. In the first survey, the prevalence rate in North East Delhi was 27.7%, which has now increased to 29.6%, and from 22% to 33% in South East Delhi, which means that there is an increase of 50%. The overall increase rate from the previous survey is 25-26%."
"This serosurvey has been done considering the overall 2 crore population of Delhi. The sample size was 15000," he added.
Shri Satyendar Jain said that positive development is that around 29% of people have recovered. "It is relieving to know that nearly 29% of the city’s population has recovered after being infected from the coronavirus. On the other hand, 70% of people in Delhi have not developed antibodies, which means that they are yet to reach the stage of herd immunity. The male population in the survey was 28.3% and the female population was 32.2%. Four age groups were formed based on which the sero-survey was conducted. Around 25% of people were below 18 years, 50% were between 18-50 years and 25% were above 50 years of age."
"The people of Delhi are being very careful in taking precautions against Corona, and so this is a very positive development. The Corona is not rising exponentially in Delhi like before," he added.
On the sample collection and the process, Shri Satyendar Jain said, "The sample selection was completely scientific, the list of those whose samples would be collected being prepared by the experts at Maulana Azad Medical College in Delhi. This depicts the criteria of the area, age group, and the process of collecting the samples. The various criteria were the age groups, male/female representation. A prevalence rate of 34.7% has been found in the people who are below 18 years of age, 28.5% in people between 18-50 years, and 31.2% in people above 50 years. The sample size has been decided based on the study that was conducted by scientists. It is for scientists to decide what the sample size should be. People belonging to every class are included in the serosurvey, people living in slums, middle-class, and upper-middle-class. There are people of all age groups and genders."
Jain said that only 29% of people have recovered in Delhi as per the serological survey, but 71% of people are still out of the count. So, even if people are coming back now, the possibility of the development of antibodies in them remains.
He said, "These people are not infected, they have recovered. Antibodies have developed in them. In the first serological survey, North East Delhi was in the first position, and now the prevalence rate has increased by 6.7% only. So, it has been observed that the areas which were on the top in the first survey, are now seen at a lower position. Similarly, areas where the prevalence rate was lower in the first survey, are witnessing an exponential increase in the prevalence rate. For instance, the 22% prevalence rate of South East Delhi has now increased by 50%, and the rate now is 33%."
The survey will start next month again from September 1. Last month, the Delhi government had announced that it will conduct the Sero Survey every month, from 1st till 5th of every month.
"The reason for a high jump in the results of the sero survey prevalence rate by 50% in South East Delhi is because the areas which witnessed a low prevalence average, are now seeing a higher rate. In one district, the rate was 27.7%, and now the increase is much lower and has gone up to 29.6%," he added.
Satyendar Jain said, "As per the scientists, the antibodies stay in your body starting from a period of 3-4 months up to 7-8 months. Along with this, T-Cells also get developed and their life is much longer. They are called memory cells and because of them, if a person is already infected by Corona in the past, it is very non-probable that he/she will get infected again."
Satyendar Jain said that there were huge variations in all the districts the last time and ranged from 18% in one place to 12% in another. This variation has now lowered. "This means that we may soon be able to achieve herd immunity in the coming months because as per scientists, herd immunity is achieved between 40-60% and we are already at 29%," he added.
"We will compare the data of the previous survey and this month's survey, and we will then analyze if more strategies need to be made and any approach that needs to be changed. We are not slowing down on preparations that we have already done. In Europe or the USA, numbers have started rising again in some of the countries of Europe. Our country saw the highest rise in the cases at 69000 cases. So, we cannot believe that Corona is over in Delhi. There was a time when the cases in Delhi were increasing by 4000 daily and the positivity ratio was 30%. It is also reassuring to see that the positivity rate in Delhi has reduced to nearly 7%, which is much lower than the national average. The situation in Delhi is improving," added Satyendar Jain.